State Route 12 is a state highway in the U.S. state of California that travels in an east–west direction from State Route 116 in Sebastopol in Sonoma County to State Route 49 just north of San Andreas in Calaveras County. The route connects the Sonoma and Napa valleys with the Sacramento–San Joaquin River Delta and the Sierra Foothills. It is constructed to freeway standards from the Fulton Road/South Wright Road stoplight in Santa Rosa, to its partial interchange with Farmers Lane.

State Route 116 (SR 116) is a state highway in the U.S. state of California in Sonoma County. The route runs from SR 1 on the Pacific coast near Jenner to SR 121 south of Sonoma.